The scarcity of human hearts available for transplant, as well as the logistics necessary to undertake heart transplant surgery, make an implantable cardiac assist device the only viable option for many heart patients. An aortic blood pump, for example, can be permanently surgically implanted in the wall of the aorta to augment the pumping action of the heart.
A known aortic blood pump includes a flexible bladder to be inflated and deflated in a predetermined synchronous pattern with respect to the diastole and systole of the patient to elevate aortic blood pressure immediately after aortic valve closure and decrease aortic blood pressure immediately before left ventricular ejection. Inflation and deflation of the bladder is accomplished by means of a supply tube connected to the bladder and to a percutaneous access device (“PAD”). The PAD is permanently surgically implanted in a patient's body to provide a through-the-skin coupling for connecting the supply tube to an extra-corporeal fluid pressure source. Electrical leads from electrodes implanted in the heart are likewise brought out through the skin by means of the PAD. The “R” wave of the electrocardiograph and the dicrotic notch are used to control the fluid pressure source to inflate and deflate the inflatable chamber in a predetermined synchronous relationship with the heart action.
The aortic blood pump acts to assist or augment the function of the left ventricle and is typically restricted to use in patients who have some functioning myocardium. The aortic blood pump does not need to be operated all the time, and in fact, can be operated periodically on a scheduled on-time, off-time regimen, or on an as-needed basis. Typically, the patient can be at least temporarily independent of the device for periods of one to four hours or more, depending on their heart function and level of activity. The general structure of known aortic blood pumps is a semi-rigid concave shell, and a flexible membrane that is integrally bonded to the outer surface of the shell, forming an inflatable and deflatable chamber. A fabric layer is then bonded over the exterior surface of the shell that projects clear of the shell forming a suture flange. These blood pumps have been tested and demonstrated to last a few million cycles.
A traditional cardiac assist device has an elongate bladder having a semi-rigid shell with walls of uniform thickness and a relatively thicker peripheral edge and a flexible, relatively thin membrane defining an inflatable chamber. At least one passage extends through the shell defining an opening in the inner surface of the shell. The flexible membrane is continuously bonded to the shell adjacent the peripheral side edge to define the enclosed inflatable chamber in communication with the passage.
Improvements on prior art blood pumps are disclosed in U.S. Publication No. 2007-0265490 A1, the entire contents of which are incorporated herein by reference. While these devices are improving both surgical success and clinical outcome, surgical implantation generally requires invasive techniques such as implantation via open thoracotomy. Thus, new instruments and methods are needed to improve surgical implantation that minimize the incision size and are amenable to rapid endovascular/thoracoscopic surgical techniques